# UART: TX, RX and a shared reference

Connect a logic-level serial adapter to a compatible board console.

**Applies to:** Non-isolated, compatible logic-level UART. TX/RX labels are from each device's own perspective; no universal header order is implied.

## When to use it

Reading development-board logs or sending simple commands over a short local connection.

## Why it works this way

UART needs no separate clock wire, but both ends must agree on baud rate and framing.

![UART: TX, RX and a shared reference — Non-isolated, compatible logic-level UART. TX/RX labels are from each device's own perspective; no universal header order is implied.](https://valleytech-black-wire-guide.pages.dev/library/wiring/uart-logic.svg)

[Open / save the original SVG](https://valleytech-black-wire-guide.pages.dev/library/wiring/uart-logic.svg)

## Connection reference

| Adapter | Target | Purpose |
| --- | --- | --- |
| TX | RX | Send data |
| RX | TX | Receive data |
| GND | GND | Common reference |

## Make the connection

1. Confirm the target's I/O voltage and the adapter's actual TX level; a supply-voltage jumper may not change TX voltage.
2. Wire with power off, then select the documented baud, data bits, parity and stop bits.
3. Start by reading logs; garbled text often indicates framing, voltage or grounding trouble.

## Check before powering

- Do not connect two TX outputs together.
- RS-232 voltage levels require a transceiver; a USB connector alone does not identify an adapter's electrical interface.

## Matching module references

This is a general interface guide; match your own hardware documentation.

## Sources & review

Source documents inspected; independent electrical and bench review pending. Reviewed 2026-09-27.

- [Analog Devices: UART communication](https://www.analog.com/en/resources/analog-dialogue/articles/uart-a-hardware-communication-protocol.html) — Hardware interface, baud rate and data framing; checked 2026-09-27
- [Analog Devices: RS-232 fundamentals](https://www.analog.com/en/resources/technical-articles/fundamentals-of-rs232-serial-communications.html) — DTE / DCE and RS-232 electrical interface; checked 2026-09-27

Original writing and diagram by Kal / Valleytech Solutions, CC BY 4.0. Manufacturer artwork and documentation retain their own rights.

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